text: A number of spelling changes are made to British Approved Names and other older nonproprietary names with an eye toward interlingual standardization of pronunciation across major languages. Thus a predictable spelling system, approximating phonemic orthography, is used, as follows:
  * ae or oe is replaced by e (e.g. estradiol vs. oestradiol)
  * ph is replaced by f (e.g. amfetamine vs. amphetamine) 
  * th is replaced by t (e.g. metamfetamine vs. methamphetamine) 
  * y is replaced by i (e.g. aciclovir vs. acyclovir)
  * h and k are avoided where possible